Russia-Ukraine updates: 2 US veterans who joined Ukrainian forces missing

Finland and Sweden -- both traditionally militarily neutral countries -- are considering a dramatic pivot in their security policy following Russia's invasion of Ukraine.

Leaders of both countries publicly stated during a joint press conference Wednesday that they are considering taking steps to join the NATO alliance.

"The European security architecture has changed fundamentally after Russia's invasion of Ukraine," Finland's Prime Minister Sanna Marin said. "The change in the security landscape makes it necessary to analyze how we best secure peace for Finland and in our region in the future."

Swedish Prime Minister Magdalena Andersson added, "We have to really think through what is best for Sweden and our security and our peace in this new situation and, of course, what is happening and the discussion in Finland is important for us to follow. Therefore, we need to have a very close contact, but we have to have a process in Sweden to think this through."

Last week, NATO Secretary-General Jens Stoltenberg said he's had close contact with political leaders of both countries and has conveyed that it's up to them whether to decide joining NATO.

"But if they apply, I expect that 30 allies will welcome them and that we will find ways to also address the concerns they may have about this interim period between (when) they have applied and until the last ratifications has taken place," Stoltenberg said.

Kremlin spokesperson Dmitry Peskov warned that further expansion of NATO to include Finland and Sweden will not contribute to security in Europe.

"In itself, the alliance is rather a tool sharpened for confrontation, this is not an alliance that ensures peace and stability," Peskov said, according to Russian state-run news agency TASS.

-ABC News' Christine Theodorou

About 1.4 million people have been left without clean running water in war-torn eastern Ukraine and an estimated 4.6 million people across the country are at risk of losing their supply, the United Nations Children's Fund reported Wednesday.

UNICEF officials said heavy fighting in eastern Ukraine, including the widespread use of explosive weapons in populated areas, has decimated a large part of the region's water systems. The agency tallied 20 separate incidents in which water infrastructure has been damaged or destroyed and warned of a "risk of complete collapse."

Damaged electrical grids have shut down water pumps and explosion-related damage to pipelines are disrupting the flow of water, according to UNICEF.

"Water is essential for life and a right for everyone," Osnat Lubrani, the U.N. resident coordinator in Ukraine, said in a statement. "The health risks, particularly for children and the elderly, caused by water stoppages are severe, as people are forced to use dirty water sources, resulting in diarrhoea and other deadly infectious diseases."

Murat Sahin, a UNICEF Ukraine representative, added that, “Young children who live in conflict zones are 20 times more likely to die from diarrheal diseases linked to unsafe water than from direct violence, as a result of war."

In hard-hit Mariupol, which has been under siege since the start of the Russian invasion on Feb. 24, thousands of residents trapped in the city are seeking any water they can find and resorting to dirty water sources, according to UNICEF. Major cities across the Donetsk and Luhansk regions are also cut off from water supplies.

The water systems in Sumy, Chernihiv and Kharkiv have also been seriously damaged, UNICEF said. An additional 340,000 people are at risk of losing their water supply from a reservoir in Horlivka in the Donetsk region that is inching closer to running dry, according to UNICEF.

Agency officials said that prior to the invasion, much of the water systems in eastern Ukraine were already ailing after eight years of a low-grade conflict in the region.

-ABC News' Christine Theodorou

Russia claimed Wednesday that more than a thousand Ukrainian soldiers had surrendered in Mariupol, a besieged port city in southeastern Ukraine that is still held by Ukrainian forces.

"In Mariupol city, near the 'Illich' Steelworks, 1,026 Ukrainian servicemen of the 36th Marine Brigade have voluntarily laid down their arms and surrendered as a result of a successful offensive by the Russian Armed Forces and Donetsk People's Republic militia units," the Russian Ministry of Defense said in a statement.

The surrendering troops included 162 officers and 47 women, according to the ministry.

"151 wounded Ukrainian servicemen of the 36th Marine Brigade received primary medical care immediately on the spot, after that they were all taken to the Mariupol city hospital for further treatment," the ministry added.

The Biden administration could announce as early as Wednesday upward of $750 million in additional military assistance to Ukraine, a U.S. official told ABC News.

The new assistance could possibly include a range of military hardware -- including howitzers, artillery and Humvees -- though the full package still needs to be finalized, the official said.

-ABC News' Luis Martinez

Correction: Mi-17 helicopters are not being considered as part of the package, as previously reported.